Update cheatsheets

tldr/linux/rtmon

@@ -0,0 +1,17 @@
+---
+syntax: markdown
+tags: [tldr, linux]
+source: https://github.com/tldr-pages/tldr.git
+---
+# rtmon
+
+> Save network state changes to a file.
+> More information: <https://manned.org/rtmon>.
+
+- Save all network state changes to a file:
+
+`sudo rtmon {{[f|file]}} {{path/to/file}}`
+
+- Specify the type of change to log:
+
+`sudo rtmon {{[f|file}} {{link|address|route}}`